1. Technical Field
This invention is related to valves and particularly to a valve useful as a standing valve or an injection valve to control flow in a well flow conductor.
2. Background Art
Many standing valves have been developed and used in well flow conductors to permit production flow to the surface when the well reservoir contains sufficient pressure, and close to protect the reservoir from damage caused by pressured flow down the conduit into the reservoir. As it is frequently later desirable to pump chemicals or water for injection into the reservoir, down through the standing valve, standing valves have been developed having a flow passage which may be permanently opened to permit pumped flow down and provide for unrestricted two way flow through the valve. An example of a VELOCITY OPERATED STANDING VALVE is shown in U.S. Pat. No. 4,352,366 to Ernest P. Fisher, Jr. A flow path around the normally closed ball valve in the Fisher standing valve may be opened for downward flow of injected fluids or upward flow of produced fluids. U.S. Pat. No. 4,441,558 to William R. Welch and Thomas J. Heard covers another form of standing valve which may be opened for upward and downward flow. U.S. Pat. No. 4,502,542 discloses a well system which utilizes a standing valve, through which a flow path may be opened to permit two way flow.